wiiqt/WiiQt/lz77.cpp

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#include "lz77.h"
//most functions here are taken from wii.cs by leathl
//they have just been tweeked slightly to work with Qt C++
LZ77::LZ77()
{
match_position = 0;
match_length = 0;
textsize = 0;
codesize = 0;
}
int LZ77::GetLz77Offset( const QByteArray &data )
{
QByteArray start = data.left( 5000 );
return start.indexOf( "LZ77" );
}
void LZ77::InitTree()
{
int i;
int N = 4096;
for( i = N + 1; i <= N + 256; i++ )
rson[ i ] = N;
for( i = 0; i < N; i++ )
dad[ i ] = N;
}
void LZ77::DeleteNode( int p )
{
int N = 4096;
int q;
if( dad[ p ] == N )
return; /* not in tree */
if( rson[ p ] == N )
q = lson[ p ];
else if( lson[ p ] == N )
q = rson[ p ];
else
{
q = lson[ p ];
if( rson[ q ] != N )
{
do
{
q = rson[ q ];
}
while( rson[ q ] != N );
rson[ dad[ q ] ] = lson[ q ];
dad[ lson[ q ] ] = dad[ q ];
lson[ q ] = lson[ p ];
dad[ lson[ p ] ] = q;
}
rson[ q ] = rson[ p ];
dad[ rson[ p ] ] = q;
}
dad[ q ] = dad[ p ];
if( rson[ dad[ p ] ] == p )
rson[ dad[ p ] ] = q;
else
lson[ dad[ p ] ] = q;
dad[ p ] = N;
}
void LZ77::InsertNode( int r )
{
int i, p, cmp;
int N = 4096;
int F = 18;
cmp = 1;
p = N + 1 + ( text_buf[ r ] == ( quint16 )0xffff ? ( quint16 )0 : text_buf[ r ] );
rson[ r ] = lson[ r ] = N;
match_length = 0;
for( ; ; )
{
if( cmp >= 0 )
{
if( rson[ p ] != N )
p = rson[ p ];
else
{
rson[ p ] = r;
dad[ r ] = p;
return;
}
}
else
{
if ( lson[ p ] != N )
p = lson[ p ];
else
{
lson[ p ] = r;
dad[ r ] = p;
return;
}
}
for( i = 1; i < F; i++ )
if( ( cmp = text_buf[ r + i ] - text_buf[ p + i ] ) != 0 )
break;
if( i > match_length )
{
match_position = p;
if( ( match_length = i ) >= F )
break;
}
}
dad[ r ] = dad[ p ];
lson[ r ] = lson[ p ];
rson[ r ] = rson[ p ];
dad[ lson[ p ] ] = r;
dad[ rson[ p ] ] = r;
if( rson[ dad[ p ] ] == p )
rson[ dad[ p ] ] = r;
else
lson[ dad[ p ] ] = r;
dad[ p ] = N;
}
quint32 LZ77::GetDecompressedSize( const QByteArray &data )
{
int off = GetLz77Offset( data );
if( off == -1 )
{
qWarning() << "LZ77::GetDecompressedSize -> no lz77 magic";
return 0;
}
QByteArray ba = data;
QBuffer buf( &ba );
if( !buf.open( QBuffer::ReadOnly ) )
{
qWarning() << "LZ77::GetDecompressedSize -> Can't create buffer";
return 0;
}
buf.seek( off + 4 );
quint32 gbaheader;
buf.seek( off + 4 );
buf.read( (char*)&gbaheader, 4 );
return ( gbaheader >> 8 );
}
QByteArray LZ77::Decompress( const QByteArray &compressed, int offset )
{
int N = 4096;
int F = 18;
int threshold = 2;
int k, r, z, flags;
quint16 i, j;
char ch;
quint32 decomp_size;
quint32 cur_size = 0;
QByteArray crap = compressed;
QBuffer infile( &crap );
if( !infile.open( QBuffer::ReadOnly ) )
{
qWarning() << "Can't create buffer 1";
return QByteArray();
}
QByteArray ret;
QBuffer outfile( &ret );
if( !outfile.open( QBuffer::ReadWrite ) )
{
qWarning() << "Can't create buffer 2";
return QByteArray();
}
quint32 gbaheader;
infile.seek( offset + 4 );
infile.read( (char*)&gbaheader, 4 );
decomp_size = gbaheader >> 8;
if( !decomp_size )
{
infile.read( (char*)&decomp_size, 4 );
}
quint8 text_buf[ N + 17 ];
//qDebug() << "decomp_size:" << decomp_size;
for( i = 0; i < N - F; i++ )
text_buf[ i ] = 0xdf;
r = N - F;
flags = 7;
z = 7;
while( true )
{
flags <<= 1;
z++;
if( z == 8 )
{
if( !infile.getChar( &ch ) )
break;
flags = (quint8) ch;
z = 0;
}
if( ( flags & 0x80 ) == 0 )
{
if( !infile.getChar( &ch ) )
break;
if( cur_size < decomp_size )
outfile.putChar( ch );
text_buf[ r++ ] = ch;
r &= ( N - 1 );
cur_size++;
}
else
{
if( !infile.getChar( &ch ) )
break;
i = (quint8)ch;
if( !infile.getChar( &ch ) )
break;
j = (quint8)ch;
j = j | ( (i << 8) & 0xf00 );
i = ( ( i >> 4 ) & 0x0f ) + threshold;
for( k = 0; k <= i; k++ )
{
ch = text_buf[ ( r - j - 1 ) & ( N - 1 ) ];
if( cur_size < decomp_size )
outfile.putChar( ch );
text_buf[ r++ ] = ch;
r &= ( N - 1 );
cur_size++;
}
}
}
return ret;
}
QByteArray LZ77::Decompress( const QByteArray &compressed )
{
int off = GetLz77Offset( compressed );
if( off < 0 )
{
qWarning() << "LZ77::Decompress -> data is not compressed";
return compressed;
}
return Decompress( compressed, off );
}
QByteArray LZ77::Compress( const QByteArray &ba )
{
//testing 1, 2
//return ba;
LZ77 lz;
QByteArray ret = lz.Compr( ba );
return ret;
}
QByteArray LZ77::Compr( const QByteArray &ba )
{
int i, len, r, s, last_match_length, code_buf_ptr;
char ch;
int code_buf[ 17 ];
int mask;
int N = 4096;
int F = 18;
int threshold = 2;
quint32 filesize = (ba.size() << 8) + 0x10;
QByteArray crap = ba;
QBuffer infile( &crap );
if( !infile.open( QBuffer::ReadOnly ) )
{
qWarning() << "Can't create buffer 1";
return QByteArray();
}
QByteArray ret;
QBuffer output( &ret );
if( !output.open( QBuffer::ReadWrite ) )
{
qWarning() << "Can't create buffer 2";
return QByteArray();
}
output.putChar( 'L' );
output.putChar( 'Z' );
output.putChar( '7' );
output.putChar( '7' );
output.write( (const char*)&filesize, 4 );
InitTree();
code_buf[ 0 ] = 0;
code_buf_ptr = 1;
mask = 0x80;
s = 0;
r = N - F;
for( i = s; i < r; i++ )
text_buf[ i ] = 0xffff;
for( len = 0; len < F && infile.getChar( &ch ); len++ )
text_buf[ r + len ] = (quint8)ch;
if( ( textsize = len ) == 0)
return ba;
for( i = 1; i <= F; i++ )
InsertNode( r - i );
InsertNode( r );
do
{
if( match_length > len )
match_length = len;
if( match_length <= threshold )
{
match_length = 1;
code_buf[ code_buf_ptr++ ] = text_buf[ r ];
}
else
{
code_buf[ 0 ] |= mask;
code_buf[ code_buf_ptr++ ] = (quint8)
( ( ( r - match_position - 1 ) >> 8) & 0x0f ) |
( ( match_length - ( threshold + 1 ) ) << 4 );
code_buf[ code_buf_ptr++ ] = (quint8)( ( r - match_position - 1 ) & 0xff );
}
if( ( mask >>= 1 ) == 0 )
{
for( i = 0; i < code_buf_ptr; i++ )
output.putChar( (quint8)code_buf[ i ] );
codesize += code_buf_ptr;
code_buf[ 0 ] = 0; code_buf_ptr = 1;
mask = 0x80;
}
last_match_length = match_length;
for( i = 0; i < last_match_length && infile.getChar( &ch ); i++ )
{
DeleteNode( s );
text_buf[ s ] = (quint8)ch;
if( s < F - 1 )
text_buf[ s + N ] = (quint8)ch;
s = ( s + 1 ) & ( N - 1 );
r = ( r + 1 ) & ( N - 1 );
InsertNode( r );
}
while( i++ < last_match_length )
{
DeleteNode( s );
s = ( s + 1 ) & ( N - 1 );
r = ( r + 1 ) & ( N - 1 );
if( --len != 0 )
InsertNode( r );
}
}
while( len > 0 );
if( code_buf_ptr > 1 )
{
for( i = 0; i < code_buf_ptr; i++ )
output.putChar( (quint8)code_buf[ i ] );
codesize += code_buf_ptr;
}
int padding = codesize % 4;
if( padding != 0 )
output.write( QByteArray( 4 - padding, '\0' ) );
infile.close();
return ret;
}